Factors associated with completion of treatment course with Lu-177 vipivotide in men with metastatic castration-resistant prostate cancer at a single institution

Summary: Lutetium-177 vipivotide tetraxetan (Lu-177 vipivotide) is a recently FDA-approved radiopharmaceutical therapy option for patients diagnosed with metastatic castration-resistant prostate cancer (mCRPC). A clinical trial has demonstrated an overall survival benefit for patients who received this radiopharmaceutical after progression on androgen deprivation therapy (ADT) and docetaxel compared to standard of care.  Careful selection in these heavily pretreated patients may help to predict the tolerability of Lu-177 vipivotide, as multiple comorbidities often preclude patients from completing a full course of therapy. In this retrospective review, we assess which factors were associated with early discontinuation of treatment. Patients with mCRPC who had progressed on ADT and docetaxel with disease that had positive uptake in prostate specific membrane antigen (PSMA) PET imaging were evaluated. Patients also underwent pre-procedure laboratory evaluation that demonstrated a white blood cell count (WBC) > 2.5 x 10e9/L, platelets ≥100 × 10e9/L, hemoglobin (Hg) ≥9 g/dL, Total bilirubin < 1.5 x the upper limit of normal (ULN), alanine aminotransferase (ALT) and aspartate aminotransferase (AST)  ≤3.0 x ULN OR × ≤5.0 ULN for patients with liver metastases, serum creatinine ≤1.5 x ULN or creatinine clearance ≥50 mL/min.   Data was gathered from review of electronic medical records. Patients were prescribed 200mCi dose every 6 weeks for 6 cycles. Laboratory evaluations were completed 1 or 2 weeks prior to each infusion of Lu-177 vipivotide. We compared the group of patients that completed all six cycles with those that did not. The Mann-Whitney U test was used for ordinal Karnofsky Performance Scale score (KPS), and the student T-test was used for all other variables. Twenty three patients were initiated on therapy with Lu-177.  10 patients completed treatment while 13 did not.. Patients who did not complete therapy completed a median of 3 cycles.  The average age was 74 years, with no difference between those who completed therapy and those who did not (71 vs 75 years, p=0.26). A determinant factor in patients that completed the treatment were those with adequate Hb levels prior to treatment (12 g/dL vs 9.3 g/dL, p = 0.001). A statistically significant association was also found between the KPS score and treatment completion. Patients who complete the treatment had a vs those who did not had a KPS of 70 and 60 (p=0.007). There is no significance when comparing platelet count and patient survival (205.0 vs 235.5 p=0.290). Even with limitations in this study such as sample size, several implications can be dissected by the results. When selecting candidates to undergo pluvicto therapy, controlling variables such as Hg and KPS score should be taken into consideration. Suggesting that patients with mCRPC would benefit from pluvicto therapy if the begin treatment at an earlier stage of disease progression. Peter Whatts (he/him/his), MD (Presenting Author) - Karmanos; Steven R. Miller, MD (Co-Author) - Detroit Medical Center/Wayne State Unive; Kevin Whatts (he/him/his), MD (Co-Author) - UMHS